1. Field of the Invention
This invention relates to an image magnifying and pick-up system incorporating a lighting system directing light on to a portion of any specimen to be observed such as, for example, the skin of a human body, its viscera or the like. Such a magnifying and pick-up system may employ an image Pick-up head section directly abutting the specimen to display a magnified image of the observed portion on a screen of a monitor.
2. Description of the Prior Art
In general, in an image magnifying and pick-up system where the outer surface of an image pick-up head directly abuts a surface of a portion of the specimen to be observed (hereinafter referred to as the "observed portion") to display a magnified image of the observed portion on a monitor screen, it is necessary to illuminate the observed portion.
When the illumination is achieved mainly by using vertical lights or by projecting illuminating light on to the surface of the observed portion (or an abutment surface of the observed portion which the pick-up head abuts in such a way that it is perpendicular to or right opposite the abutment surface), the abutment surface of the observed portion tends to reflect relatively :he illuminating light. This causes an observed portion which reflects the light relatively highly to appear very white when projected on to the screen of a monitor, resulting in an unsatisfactory visual impression of the colors and fine detail of the observed portion.
When the illumination is achieved mainly by using horizontal light or by directing illuminating light in parallel to the abutment surface of the observed portion, it is not possible to provide sufficient illumination to any fine recesses in the abutment surface. This therefore causes the recess to be displayed relatively darkly on the screen of the monitor, making effective and accurate inspection of the observed portion impossible.
In order to solve these problems, the present applicants recognized the need for an illuminating or lighting means able to project illumination mainly consisting of horizontal light, but to which vertical light is added in an amount appropriately balanced with the horizontal light onto the surface of the observed portion of the specimen. It was also noted that when the specimen -o be observed has a property of transmitting the illuminating light to a certain degree (e.g. human skin or its viscera), the lighting means should also allow adjustment of the balance between vertical light and horizontal light, taking the amount of light transmitted through the specimen into consideration.
Conventional lighting light-guide devices in image magnifying and pick-up systems provide illumination mainly using horizontal light as described above; they therefore fail to meet the requirements outlined above. A lighting lightguide device was therefore proposed which generally includes a transparent cylindrical light-guide body, and a flat disc formed of a transparent light-guide material, mounted at the distal end of the light-guide body through a reflecting surface surrounding the body. It has a central observation aperture in the form of a small hole, so that illuminating light guided through the cylindrical light-guide body to its distal end is refracted on the reflecting surface so as to be directed towards the central axis of the disc. It therefore radiates in the form of horizontal beams from the overall peripheral surface of the observation aperture to illuminate the observed portion of a specimen in the observation aperture.
Unfortunately, this construction necessarily results in only horizontal light constituting the illumination and fails completely to use vertical light and so transmitted light in amounts balanced with the horizontal light.
Also, in this light-guide device, the outer surface of the image pick-up head which abuts the observed portion of the specimen is flat, since it takes the form of a flat light-guide disc. Accordingly, the abutment surface of the observed portion of the specImen is limited to a configuration which is compatible with the outer surface of the head, i.e. a generally convex or flat shape. This causes applications of the light-guide device to be limited.